I started the day with a viewing of the David Bowie collection which is being shown in Sotheby’s for a few days before going to Los Angeles, New York and Hong Kong.   What was immediately obvious was how serious he was as a collector – thoughtful and well informed, with a good eye for modern British work, including an early sketch of Lytton Strachey by Henry Lamb (why, one wonders, was Strachey being drawn so early in his career ?), a beautiful small Family Group by Henry Moore, good work by Kenneth Armitage and Peter Lanyon, and a fine Auerbach of his cousin, Gerda Boehm.   The sale is not till November.